In valve devices for controlling the level to which tanks may be filled with liquid, it heretofore has been known to utilize a fluid pressure operated valve to control flow of liquid into the tank and to use a jet type sensor for controlling opening and closing of the valve according to the level of the liquid within the tank. Such devices are disclosed, for example, in U.S. Pat. Nos. 3,020,924 and 3,168,105 and in French Pat. No. 313524 published June 15, 1956.
In these devices, the jet sensors include a nozzle and a receiver, the receiver being axially aligned with, but spaced from the nozzle. Part of the liquid under pressure from the valve inlet is diverted to the nozzle and discharged therefrom in a jet stream that is received by the receiver with substantially no pressure loss when the level of liquid within the tank is below the jet stream and is transmitted to one side of a valve actuator for holding the valve open. When the liquid level rises so as to cause submerging of the jet stream, the stream is diffused whereby relatively little or no pressure is received by the receiver for transmittal to the actuator and the valve then closes by spring and/or fluid pressure.
In U.S. Pat. No. 3,168,105 the nozzle and receiver are vertically aligned when installed and there is a shroud that extends from the nozzle and which has an open end that surrounds and axially overlaps the receiver. A pickup tube connects to the interior of the shroud and has a free open end below both the shroud open end and the receiver inlet. When the liquid level in the tank reaches the lower end of the tube, liquid is drawn through the tube into the shroud by aspirating action of the jet stream between the nozzle and receiver but not enough to diffuse the stream. Closing action starts to occur when the liquid level in the tank reaches the open end of the shroud but because of the vertical arrangement, the submersion and diffusion of the jet stream is gradual and therefore the closing action of the valve is not rapid and variation in shutoff level can occur, particularly if there is variation in the supply pressure. When the tank level falls, the shroud will remain full of liquid and diffuse the jet until the open end of the pickup tube is uncovered and therefore the valve will not reopen until there has been a substantial drop in the tank level. This eliminates frequent cycling of the valve.
In U.S. Pat. No. 3,020,924, the nozzle and receiver are horizontally aligned and the consequently horizontal jet stream will be completely submerged and diffused quickly by the rising level of liquid in the tank with rapid shutoff of the valve. However, there is no shroud and pickup tube so that the jet stream will be quickly reestablished upon a slight drop in the tank level and frequent cycling of the valve can occur.
In the French patent, a hand-held filling nozzle is disclosed in which the direction of the jet stream may approach horizontal and there is a shroud and pickup tube. However, the valve must shutoff before the liquid level reaches the jet stream to avoid spilling liquid from the tank. This is accomplished by overlapping the receiver with the shroud to restrict flow of liquid from the shroud and hence jet stream diffusion and valve shutoff occurs when the lower end of the tube becomes submerged and liquid is drawn up the tube and into the shroud. In such case shutoff is not as rapid or as accurate as when the jet is submerged by the rising liquid level in the tank. The hand-held nozzle is not intended to provide for reopening the valve upon drop in the tank level but if the device were adapted to such use reopening would occur when level dropped below the bottom of the tube and hence there would be rapid cycling of the valve between open and closed positions.